1. The Field of the Invention
The present invention relates generally to separation of analyte species in an analyte sample. More particularly, the present invention relates to a fraction collector configured for separating and collecting an analyte species from an analyte sample containing a plurality of analyte species and enabling such a separation on a continuous basis if desired.
2. Description of Related Art
The ability to separate a particular analyte species from an analyte sample is a common requirement in biological research. Likewise being able to separate a particular substance from a mixture of substances is often a requirement in pharmaceutical manufacturing. For example, the ability to separate an individual protein from a mixture of proteins is desirable in research and in the manufacturing of certain medicaments. For convenience, the terms “analyte” and “analyte species” will be used herein to refer to a sample containing a plurality of different substances, and the individual substances, respectively. Typically, these will be substances comprising molecules having a net charge (e.g. protein molecules, amino acid molecules, and DNA molecules).
HPLC, gel electrophoresis and CE typically offer a “single pass” means of separating a mixture of substances into separate substances or isolating a particular substance or group of substances. However, it is generally not efficient to do multiple separations to increase the quantity of obtained sample of one substance separated out from the sample mixture. A more efficient method is to provide a continuous separation. One method of doing this is called “Simulated Moving Bed” or SMB, which consists of switching segments of a conventional separation column in such a manner that the apparatus will allow a continuous fluid mixture including analyte to be flowing into one end of the column, and a continuous flow of a separated analyte species from the column output, while a second output discharges the remainder of the fluid mixture. Most SMB apparatus configurations comprise many packed columns, each similar to an HPLC column, for example, which are switched sequentially at time intervals to simulate a counter-flowing moving bed.
For continuous separation of analyte species, e.g. individual proteins, in complex analyte mixtures, conventional SMB processes do not work well because the HPLC columns have limited resolution, and conventional known substitutes for this method are likewise limited. Even for relatively simple analyte sample mixtures, the stationary phases used in a conventional SMB require a relatively large amount of development time to optimize the separation; and, in some instances, the stationary phase in the columns becomes very expensive.